The present invention is concerned with a vaccine suitable for in ovo vaccination against Newcastle Disease infection, with the use of a Newcastle Disease Virus strain in the preparation of such a vaccine, as well as with the protection of poultry against Newcastle Disease infection by in ovo vaccination with a vaccine containing a Newcastle Disease virus train.
In ovo vaccination of virus-containing vaccines was extensively described by Sharma et al. (U.S. Pat. No. 4,458,630). In particular it teaches that live Marek""s disease virus can be injected into amniotic fluid within the egg, whereafter the embryo is infected and the vaccine virus replicates to a high titer which induces the formation of protective antibodies in the treated embryo. (Sharma; Avian Diseases 29, 1155, 1167-68 (1985).
In U.S. Pat. No. 5,427,791 Ahmad et al. describe the embryonal vaccination against Newcastle Disease. Herein, in order to provide for a non-pathogenic attenuation of the live Newcastle Disease virus (strain NDV-B 1), the viruses were modified through use of ethyl methane sulfonate (EMS).
A disadvantage of this type of modification is the fact that EMS is a mutagen and that the vaccine is suspected to act as a mutagen as well, which is undesirable for regular administration of the vaccine. On the other hand, untreated NDV-B 1 cannot be applied for in ovo vaccination as almost all of the embryos will die upon injection of the eggs with this unmodified virus.
Furthermore, it has been found that the margin between minimum effective dose and the maximum dose for safety for these modified viruses is less than 10 (hence less than log1). For practical purposes and in view of the errors as a result of production and due to losses during storage, this margin is too small.
Surprisingly it has been found that a vaccine preparation containing Newcastle Disease viruses of the strain NDW is particularly suited for in ovo application. Hence the present invention is concerned with the use of Newcastle Disease virus of the strain NDW in the in ovo vaccination of poultry. As a further embodiment the invention is concerned with the use of Newcastle Disease virus of the strain NDW in the preparation of a vaccine suitable for in ovo administration poultry.
Samples of the Newcastle Disease virus strain NDW were deposited at CNCM of Institut Pasteur under No 781. See EP 351908.
Advantageously, the NDW strain is administered in an amount of between 10xe2x88x921 and 103 and more in particular in an amount between 10xe2x88x920.7 and 102.2 per egg.
For obtaining the best results in immunisation it was found that the NDW containing vaccine can be administered in ovo at between 17 and 19 days of incubation, preferably at 18 days of incubation.